The present invention relates to a process for polymerizing or copolymerizing .alpha.-olefins in high activity and high stereospecificity using a novel catalyst.
Catalysts comprising titanium halides and organoaluminum compounds have heretofore been known as catalysts for polymerizing .alpha.-olefins in high stereo-specificity. In the polymerization using such catalysts, however, the catalysts remain in considerable amounts in the resultant polymers because of low catalytic activity, so it is necessary to remove the residual catalysts, although there are obtained highly stereo-specific polymers.
Recently, various proposals have been made for improving the catalytic activity. According to these proposals, a high activity catalyst is obtained by using a catalyst component comprising an inorganic solid carrier such as MgCl.sub.2 and titanium tetrachloride supported thereon.
In the preparation of polyolefins, however, it is preferable that the catalytic activity be as high as possible, and so a catalyst of higher activity has been demanded. It is also important that the proportion of atactic portion in the resultant polymer be as small as possible.
In the above proposed methods, olefin polymers are usually obtained in a state of slurry, but from the standpoint of utilization efficiency of the reaction vessel, the higher the bulk density of the resultant olefin polymers, the more advantageous.